Data storage capacities of rewritable data storage cartridges, such as magnetic tape cartridges have substantially increased over time. The tracking of the stored data of rewritable data storage cartridges is typically accomplished by the use of indexes, etc., which themselves require substantial data storage. In one example, the index may comprise higher speed data storage. In another example, the index for data of a rewritable data storage cartridge is stored on a separate partition of the cartridge from the data. In some examples, the partitions may be physical partitions, for example, defined and separated by guard bands on a magnetic tape. Storing the index on the cartridge makes the cartridge “self-describing”. An application may update data stored by the cartridge and should update the index describing that data.
A risk occurs if a “self-describing” cartridge is accessed by an application that is unaware that the cartridge is “self-describing”. Thus, the application could write append to the data, and, without knowledge of the index, would not update the index, leaving the stored data and the index out of synchronization.
The default position for SCSI (small computer systems interface) is a location corresponding to the beginning of partition 0. One way to provide protection from the append problem would be to put the index in partition 0 and the data in partition 1. The disadvantage of such an approach is that it denies any access to the data for an application that is not partition aware. It is advantageous to put the data in partition 0 to provide read access to applications that are not partition aware, but results in the write append risk.